donaldson



(No Model.) Y R.B. DONALDSON.

DENTAL INSTRUMENT.

Patented July 14,1885- WITNBSSES:

f ATTORNEY 'ROBERT B. DONALDSON, WASHINGTON, DISTRICT OF COLUMBIA.

DENTAL INSTRUMENT.

SPECIFICATION forming part of Letters Patent No. 322,265, dated July 14, 1885.

' Application mm1 May 5, isst. (No model.)

To a/ZZ whom it may concern:

Be it known that I, ROBERT BRUCE DON- ALDsoN, of Washington, in the District of Columbia, have invented a new and useful Improvement in Dental Instrument-srand I do declare that the following is a full andaccurate description of the same, reference being had to the accompanying drawings, wherein- Figure 1 is a perspective view of my instrument greatly enlarged. Fig. 2 represents the same operative size. Fig. 3 represents the same operative size bent to illustrate how it `may be prepared for use.

scrape and cleanse the walls of the canal.l

These instruments are generally made by the dentist himself, the barbs being formed by a knife or ne file. The action of such an instrument is irregular and uncertain, and the barbs frequently break off in the canal and are difficult to remove. To remove as far as possible the liability of breaking, the instrument is generally made from untempered metal, and this detracts from the efficiency.

My invention consists of an instrument, which I prefer to make from piano-wire, reduced at the point to a requisite size to enter the nerve-canal, and provided at and near its point with a series of scraping-teeth, projecting in all directions, and preferably arranged in a spiral line around kthe shaft of the instrument.

In the drawings, A is the shaft of the instrument, about two and a half inches in length, and provided with a suitable handle, B. Piano -wire has a temper admirably adapted for instruments of this description.

It is sufficiently hard for all purposes, yet i is tough and iieXible, and will bear repeated bendings. I therefore prefer to make the shaft from steel piano-wire of proper gage,

reduced toward its extremity to the proper" I then make a series.

degree of attenuation. y of cuts, d, inclined to the axis of the shaft A, which separate portions of the metal of said shaft and bend it outwardly, as shown; and

other from that accidentally too deep penei w tration which causes the barb of the ordinary y instrument to be broken off.

I prefer to arrange the Scrapers e in a 'will canse the instrument to embed itself,

and thereby'render the removal of the nerve substance comparatively easy.

Having described my invention, I claim as newl. A dental instrument for scraping and cleaning the nerve-canal in the root of a tooth, consisting of a substantially rigid shaft, A, provided on all sides with a series of inclined cuts, d, and projecting Scrapers e, substantially as set forth.

2. A dental instrument for scraping and cleaning the nerve-canal in the root of a tooth, consisting of a substantially rigid shaft,

A, provided with aseries of cuts, d, and resultant Scrapers c, inclined to the axis of said shaft and arranged on a spiral line around the same.

3. A dental instrument for scraping and cleaning the nerve-canal of a tooth, consisting of a substantially rigid shaft, A, of steel y piano-wire,'reduced to the desired attenuation toward thepoint, and provided with a series of inclined cuts, d, and projecting Scrapers e, substantially as set forth.

ROBERT DONALDSON.

Witnesses:

JAMEs I. STABLER, ALBERT G. HALL. 

